Process for forming deposition film

ABSTRACT

A process for forming a deposition film on a substrate comprises introducing separately a precursor or activated species formed in a decomposition space (B) and activated species formed in a decomposition space (C), into the deposition space wherein the film is formed on the substrate.

This application is a continuation of application Ser. No. 889,606,filed July 28, 1986, which, in turn, is a continuation of applicationSer. No. 641,021, filed on Aug. 15, 1984, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a process for forming functional films,particularly deposition useful for various purposes, specially forsemiconductor devices and electrophotographic photosensitive devices.

2. Description of the Prior Art

A number of possible processes have been disclosed up to now for formingdeposition films. For instance, for producing films of amorphous silicondeposit, there have been tried the vacuum deposition process, plasma CVDprocess, CVD process, reactive sputtering process, ion plating processand photo-CVD process, etc. Generally, the plasma CVD process isindustrialized and widely used for this purpose.

However, deposition films of amorphous silicon still admit ofimprovements in overall characteristic including electric and opticalproperties, various characteristics to fatigue due to repeated uses orto environmental use conditions, and additionally productivity includingproduct uniformity, reproducibility, and mass-productivity.

The conventional plasma CVD process, as compared with the conventionalCVD process, is complicated in the reaction process to deposit amorphoussilicon and involves many unknown things in the reaction mechanism. Thefilm formation in the plasma CVD process is affected by a number ofparameters (e.g. substrate temperature, flow rates and mixing ratio offeed gases, pressure during film formation, high-frequency power used,electrode structure, structure of deposition chamber, rate ofevacuation, and plasma generation method). These various parameters,combined with one another, cause sometimes an unstable plasma, whichexerts marked adverse effects on the deposited film. In addition, theparameters characteristic of the deposition apparatus must be determinedaccording to the given apparatus, so that it is difficult in practice togeneralize the production conditions.

The conventional plasma CVD process is regarded at the present time asthe best method for the purpose of obtaining amorphous silicon filmswhich have such electrical and optical properties as to fulfill variousapplication purposes.

However, it is necessary in certain applications of the deposition filmto realize reproducible mass production thereof while satisfying needsfor the film of a large area, uniform thickness, and uniform quality. Inconsequence, much investment is required for the mass productionequipment, the administration items for the mass production becomecomplicated, tolerances in quality control become narrow, and theregulation and adjustment of equipment becomes delicate. These mattersin the production of amorphous silicon deposit films by the plasma CVDprocess are pointed out as the problems to be solved in the future.

On the other hand, the conventional CVD process requires a highoperational temperature and has not given the deposition film havingsuch characteristics that the film can be used practically.

Thus there is an intensive need for a process for producing amorphoussilicon films which, as stated above, realizes mass production thereofat a low equipment cost while securing practically acceptablecharacteristics and uniformity of the films.

The above stated matters also apply to other functional films, e.g.silicon nitride, silicon carbide, and silicon oxide films.

SUMMARY OF THE INVENTION

An object of the invention is to provide a novel process for formingdeposition films which is free of the above noted drawbacks of theplasma CVD process.

Another object of the invention is to provide a process by whichdeposition films of good characteristics can be formed at an improveddeposition rate without utilizing plasma reaction in the depositionspace (A) for the film formation and additionally the simplification ofcontrolling the film formation conditions and mass production of thefilms can be achieved with ease.

According to an aspect of the invention, there is provided a process forforming a deposition film on a substrate which comprises introducingseparately a precursor formed in a decomposition space (B) and activatedspecies formed in another decomposition space (C), into the depositionspace (A) wherein the film is formed on the substrate.

According to another aspect of the invention, there is provided aprocess for forming a deposition film on a substrate which comprisesintroducing separately activated species formed in a decomposition space(B) and activated species formed in another decomposition space (C),into the deposition space (A) wherein the film is formed on thesubstrate.

According to a further aspect of the invention, there is provided aprocess for forming a deposition film on a substrate which comprisesintroducing separately activated species (a) which are prepared bydecomposing a silicon halide represented by the formula Si_(n) X_(2n+2)(n=1, 2, . . . ) and a mixture of activated species of hydrogen withactivated species (b) represented by the formula Si_(m) H_(2m-x) (m=1,2, . . . , x=1, 2, . . . ), the mixture being prepared by decomposing ahigher, straight chain silane compound, into the deposition space (A)wherein the film is formed on the substrate.

According to still another aspect of the invention, there is provided aprocess for forming a deposition film on a substrate which comprisesintroducing separately activated species (a) which are prepared bydecomposing a silicon halide represented by the formula Si_(n) X_(2n+2)(n=b 1, 2, . . . ) and a mixture of activated species of hydrogen withactivated species (b), the mixture being prepared by decomposing acyclic silane compound, into the deposition space (A) wherein the filmis formed on the substrate. As employed herein, n, m, and x are eachintegers of at least 1.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating the layer structure of anembodiment of the photoconductive member prepared according to theprocess of the invention.

FIG. 2 is a schematic illustration showing an example of the device tocarry out the process of the invention.

FIG. 3 is a schematic diagram of an arrangement which will permitindustrial mass production of deposition films according to the processof the invention.

FIG. 4 is a schematic diagram of another example of the device to carryout the process of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the process of the invention, the parameters affecting the formationof deposition films are amounts of a precursor and activated speciesintroduced into the deposition space (A), temperatures of the substrateand the space (A), and pressure therein, since no plasma is formedtherein. Accordingly, the formation of deposition films is easy tocontrol, and reproducible films can be mass-produced.

The term "precursor" herein means an intermediate that is formed priorto the ultimate product (a material constituting the deposition film)and will be converted completely or partly into a material constitutingthe ultimate product, though having, in the intact energy state, no orlittle ability to form the deposition film.

The term "activated species" herein means chemical species, for example,radicals or ions which lie in high energy states and will act chemicallyone upon another to form a deposition film on a substrate or willundergo chemical interaction or reaction with molecules of the precursorto give energy thereto, for instance, and thereby will bring theprecursor to such states as to form a deposition film. Accordingly theactivated species in the former case needs to contain a constituentwhich will be converted into a constituent of the deposition film, whilethe activated species in the latter case may or may not contain such aconstituent.

In the invention, the precursor or activated species to be introducedfrom the decomposition space (B) into the deposition space (A) areselected as desired from those of lifetimes, in the case of theprecursor, of at least desirably 0.01 sec., preferably 0.1 sec.particularly preferably 1 sec., and in the case of the activatedspecies, of at least desirably 1 sec., preferably 10 sec., particularlypreferably 150 sec. Constituents of the precursor or of the activatedspecies are converted into main constituents of the deposition film tobe formed in the deposition space (A).

When a precursor is introduced from the decomposition space (B), theactivated species to be introduced from the decomposition space (C) isselected from those of lifetimes of up to desirably 10 sec. preferably 8sec., particularly preferably sec. This activated species undergoeschemical interaction in the deposition space (A) with the precursorintroduced at the same time from the decomposition space (B) to thedeposition space (A), which precursor contains a constituent that willbecome main constituent of the intended deposition film. Thus, a desireddeposition film is readily formed on a given substrate.

When an activated species is introduced from the decomposition space(B), the activated species to be introduced from the decomposition space(C) is of short lifetimes. The activated species undergoes chemicalinteraction in the deposition space (A) with the activated speciesintroduced at the same time from the decomposition (B) to the depositionspace (A), which contains a constituent that will become mainconstituent of the resulting deposition film. Thus an intendeddeposition film is readily formed on a given substrate.

According to the process of the invention, the deposition film formedwithout generation of any plasma in the deposition space (A) suffersfrom no substantial adverse effect of the etching action or some otheraction, e.g. abnormal discharge action. In addition, more stableproduction of deposition films becomes possible according to the processof the invention, which is an improved CVD process, by controlling theatmospheric temperature of the deposition space (A) and the temperatureof the substrate, as desired.

A difference of the process of the invention from the conventional CVDprocess is to use a precursor and activated species which have beenproduced in advance in spaces other than the deposition space (A). Inthis way, the process of the invention has been markedly improved in thefilm deposition rate over the conventional CVD process. Additionally,the substrate temperature during film deposition can be further lowered.Thus, deposition films of definite quality can be produced industriallyin a large volume and at a low cost.

The formation of activated species in the decomposition space (C) can beaccomplished by exciting the charged material with not only any ofsuitable energies including electric discharge energy, light energy,thermal energy, and combined energies of these but also a heterogeneousor homogeneous catalyst.

The material to be fed into the decomposition space (B) is a compoundcontaining at least one silicon atom which combines with a highlyelectron attractive atom or atomic group, or polar group. Such compoundsmay include, for example, Si_(n) X_(2n+2) (n=1, 2, 3, . . . , X=F, Cl,Br, I), (SiX₂)_(n) (n≧3, X=F, Cl, Br, I), Si_(n) HX_(2n+1) (n=1, 2, 3, .. . , X=F, Cl, Br, I), and Si_(n) H₂ X_(2n) (n=1, 2, 3, . . . , X=F, Cl,Br, I). Individual examples of these compounds are SiF₄, Si₂ F₆, Si₃ F₈,Si₂ Cl₆, Si₂ Cl_(f) 3 F₃, (SiF₂)₅, (SiF₂)₆, (SiF₂)₄, SiHF₃, SiH₂ F₂,SiCl₄, (SiCl₂)₅, SiBr₄, and (SiBr₂)₅, which are gaseous at ordinarytemperature or readily gasifiable compounds. SiH₂ (C₆ H₅)₂, SiH₂ (CN)₂and the like are also used depending upon application purposes of thedeposition film. A precursor or activated species are formed by applyingenergy for decomposition such as thermal energy, light energy, orelectric discharge energy to the above-cited compound in thedecomposition space (B). The precursor or activated species areintroduced into the deposition space (A). The precursor to be introduceddesirably need to have a lifetime of at least 0.01 sec. By introducingsuch a precursor into the deposition space (A), the activating reactionthereof with the activated species introduced from the decompositionspace (C) is made more effective and the deposition efficiency anddeposition rate are increased, where thermal, light or other energy isapplied if necessary onto the substrate or to the atmosphere in thedeposition space (A) without using such electric discharge energy as toform plasma. Thus the formation of a desired deposition film isaccomplished.

The activated species introduced from the decomposition chamber (B) needto have lifetimes of at least 1 sec., preferably 10 sec., particularlypreferably 150 sec. With these active species, the formation of adesired deposition film is accomplished similarly to the case with theprecursor stated above.

Feed materials for preparing activated species in the decompositionspace (C) may include, for example; H₂, SiH₄, SiH₃ F, SiH₃ Cl, SiH₃ Br,SiH₃ I and the like; higher silane compound such as Si₂ H₆, Si₃ H₈, Si₄H₁₀ and the like; branched chain silane compound such asSiH₃.SiH(SiH₃)SiH₂.SiH₃ and the like; cyclic silane compound such as(SiH₂)₅, (SiH₂)₄, (SiH₂)₆, (SiH₂)₅.SiH.SiH₃ and the like; and rare gassuch as He, Ar, and the like. These materials may be used singly or incombination.

The amount ratio of feeding to the deposition space (A) of the precursoror activated species from the decomposition space (B) to the activatedspecies from the decomposition space (C) is chosen appropriatelydepending upon the deposition conditions and the kinds of activatedspecies. The ratio is generally 10:1-1:10 , preferably 8:2-4:6 (flowrateratio).

For producing the precursor or activated species in the decompositionspace (B) or (C), electric discharge energy, thermal energy, lightenergy, or some other energy is used as excitation energy inconsideration of operating conditions and equipment in individual cases.

When a higher straight chain silane or a cyclic silane is used as thematerial to be fed into the decomposition space (C), it can bedecomposed at a much higher rate and with lower energy and the rate offilm deposition can be increased further to a great extent. Accordingly,a steady and high-volume production of deposition films can beaccomplished more easily.

Now the invention is illustrated referring to a typical example ofelectrophotographic image forming members which are produced by thedeposition film forming process of the invention.

FIG. 1 shows the structure of such a typical example. Thephotoconductive member 100 shown in FIG. 1 can be used as anelectrophotographic image forming member having a layer structureconsisting of a substrate 101 suitable for photoconductive member, anintermediate layer 102 and a surface layer 104 which may be formed asrequired, and a photoconductive layer 103.

The substrate 101 may be either an electric conductor or an electricinsulator. Suitable materials for the conductive substrate are, forexample, metals such as NiCr, stainless steel, Al, Cr, Mo, Au, Ir, Nb,Ta, V, Ti, Pt, and Pd and alloys of these metals.

For the insulating substrate there may be employed usually a film orsheet of a synthetic resin, for example, polyester, polyethylene,polycarbonate, cellulose acetate, polypropylene, poly(vinyl chloride),poly(vinylidene chloride), polystyrene, and polyamide, glass, ceramics,paper and the like. It is desirable that at least one side of theinsulating substrate be given conductivity by some suitable treatmentand then overlaid H) with other necessary layers. For instance, thesurface of the substrate is covered with a thin film of NiCr, Al, Cr,Mo, Au, Ir, Nb, Ta, V, Ti, Pt, Pd, In₂ O₃, SnO₂, or ITO (In₂ O₃ +SnO₂)when the substrate is made of glass; and the surface is treated with ametal, for example, NiCr, Al, Ag, Pb, Zn, Ni, Au, Cr, Mo, Ir, Nb, Ta, V,Ti, or Pt by vacuum deposition, electron-beam vapor deposition,sputtering or the like or laminated with a foil of the above metal whenthe substrate is a synthetic resin film such as a polyester film. Theshape of the substrate is free to select as desired from cylindricalform, belt form, plate form, etc. For example, the substrate to be usedfor an electrophotographic image forming member for high-speedcontinuous copying is desired to be in endless belt form or hollowcylindrical form.

The intermediate layer 102 comprises, for example, a non-photoconductiveamorphous material containing silicon atom and any of carbon, nitrogen,oxygen, and halogen atoms. This layer has the function of preventingeffectively the inflow of charge carriers into the photoconductive layer103 from the substrate 101 side and facilitating the passage from thephotoconductive layer 103 side to the substrate 101 side, ofphotocarriers which are produced in the photoconductive layer 103 byirradiating it with electromagnetic waves and move toward the substrate101.

When the intermediate layer 102 is formed, a continuous operation ispossible up to the formation of the photoconductive layer 103. In thiscase, starting gases for forming the intermediate layer 102, each mixedif necessary with a diluent gas such as He or Ar, are fed intoprescribed decomposition spaces (B) and (C), respectively. Then,necessary excitation energies are applied to the gases in the spaces,respectively, to produce a precursor or activated species in the space(B) and activated species in the space (C). These are introduced into adeposition space (A) wherein the substrate 101 is set in advance, andthe intended intermediate layer 102 is formed on the substrate 101, ifnecessary, by applying further energy for film formation to theintroduced gases.

Effective materials as the feed to the decomposition space (C) forproducing activated species to form the intermediate layer 102 are asfollows: Ar, He, H₂, SiH₄ ; hydrogen-rich halogenated silanes, e.g. SiH₃Cl, SiH₃ F, and SiH₃ Br; higher straight chain silanes, e.g. Si₂ H₆, Si₃H₈, and Si₄ H₁₀ ; cyclic silanes, e.g. (SiH₂)₅ and (SiH₂)₄ ; andmixtures of cyclic silane, hydrogen and higher straight chain silane;gaseous or gasifiable nitrogen compounds such as nitrogen, nitride andazide, e.g. N₂, NH₃, H₂ N.NH₂, HN₃, and NH₄ N₃ ; C₁ -C₅ saturatedhydrocarbons, e.g. methane, ethane, propane, n-butane, and pentane; C₂-C₅ ethylenic hydrocarbons, e.g. ethylene, propylene, butene-1,butene-2, isobutylene, and pentene; C₂ -C₄ acetylenic hydrocarbons, e.g.acetylene, methylacetylene, and butyne; and oxygen compounds, e.g. O₂,O₃, CO, CO₂, NO, NO₂, and N₂ O.

The starting material for forming the intermediate layer 102 is selectedappropriately from the above-cited compounds so that prescribed atomswill be contained as constituents in the resulting intermediate layer102.

On the other hand, effective materials as the feed to the decompositionspace (B) for producing a precursor or activated species to form theintermediate layer 102 are, for example, SiF₄ and SiH₂ F₂, which atelevated temperature readily produce a precursor such as SiF₂ having along lifetime or activated species.

The thickness of the intermediate layer 102 is desirably 30-1000 Å,preferably 50-600 Å

The photoconductive layer 103 comprises an amorphous silicon, a-SiX(H),which comprises silicon atoms as the matrix and contains halogen atoms(X) and, if necessary, hydrogen atoms (H) so as to possess suchphotoconductive characteristics that the resulting member can exhibitsufficient functions as an electrophotographic image forming member.

For the formation of the photoconductive layer 103, a starting gas suchas SiF₄ or Si₂ H₂ F₂ is fed, similarly to the case of the intermediatelayer 102, into the decomposition space (B) and decomposed at anelevated temperature to produce a precursor or activated species. Thisprecursor or these activated species are introduced into the depositionspace (A). Into the decomposition space (C), on the other hand, astarting gas such as H₂, SiH₄, SiH₃ F, Si₂ H₆, Si₃ H₈, (SiH₂)₅, (SiH₂)₄,(SiH₂)₆, or mixture of these compounds is fed and excited with aprescribed energy to produce activated species. These activated speciesare introduced into the deposition space (A) and undergo chemicalinteraction with the precursor or activated species introduced thereintofrom the decomposition space (B), to deposit the intendedphotoconductive layer 103 on the intermediate layer 102.

Generally the thickness of the photoconductive layer 103 is chosenappropriately according to the application purpose of the end product.The thickness of the photoconductive layer 103 shown in FIG. 1 is chosenappropriately in relation to the thickness of the intermediate layer 102so as to enable the two layers to exhibit respective functionseffectively. In general, the thickness of the photoconductive layer 103is desired to be hundreds-thousands times or more as large as that ofthe intermediate layer 102. Absolute values of the suitable thickness ofthe photoconductive layer 103 are preferably 1-100 μ, more preferably2-50 μ.

The content of each of H and X (X is halogen atom such as F) in thephotoconductive layer 103 is desirably 1-40 atomic %, preferably 5-30atomic %.

The surface layer 104 shown in FIG. 1 may be formed, if necessary,similarly to the intermediate layer 102 or the photoconductive layer103. For making the surface layer 104 of silicon carbide, a startinggas, e.g. SiF₄, is fed into the decomposition space (B) and a startinggas, e.g. a SiH₄ /CH₄ /H₂ mixture, SiH₄ /SiH₂ (CH₃)₂ mixture, Si₂ H₆/CH₄ /H₂ mixture, Si₂ H₆ /SiH₂ (CH₃)₂ mixture, (SiH₂ /CH₄ /H₂ mixture,or (SiH₂)₅ /SiH₂ (CH₃)₂ mixture, is fed into the decomposition space(C). The gas introduced into each space is decomposed with excitationenergy into a precursor or activated species in the respective spacesand separately introduced into the deposition space (A) to deposit theintended surface layer 104 on the photoconductive layer 103.

A preferred example of the surface layer 104 is a deposition film, suchas a silicon nitride film or silicon oxide film, having a wide band gap.It is also possible to change the film composition continuously from thephotoconductive layer 103 to the surface layer 104. The thickness of thesurface layer 104 is in the range of desirably 0.01 to 5 μ, preferably0.05 to 1 μ.

For making the photoconductive layer 10 of n-type or p-type as required,during the layer formation, it is doped with a n-type impurity, orp-type impurity, or both impurities while controlling the dopingcontent.

Suitable p-type impurities for the doping are elements of group III-A ofthe periodic table, e.g. B, Al, Ga, In, and Tl. Suitable n-typeimpurities are elements of group V-A of the periodic table, e.g. N, P,As, Sb, and Bi, among which B, Ga, P, and Sb are best suited.

Suitable contents of the doping in the photoconductive layer 103 aredetermined according to the electric and optical characteristicsrequired for the layer. In the case of elements of group III-A of theperiodic table, the suitable contents thereof are 3×10³¹ 2 atomic % andless, and in the case of elements of group V-A, the suitable contentsthereof are 5×10⁻³ atomic % and less.

The doping of the photoconductive layer 103 with an impurity can beaccomplished by feeding a starting material for introducing the dopingimpurity in the gaseous state into the decomposition space (B) or (C) atthe time of the formation of the layer. Preferably, the material is fednot into the space (B) but into the space (C), from which activatedspecies are introduced into the deposition space (A).

Suitable starting materials for the doping impurity are compounds whichare gaseous at ordinary temperature and pressure or at least readilygasifiable under the conditions of forming the layer. Examples of suchstarting materials are PH₃, P2H₄, PF₃, PF₅, PCl₃, AsH₃, AsF₃, AsF₅,AsCl₃, SbH₃, SbF₅, BiH₃, BF₃, BCl₃, BBr₃, B₂ H₆, B₄ H₁₀, B₅ H₉, B₅ H₁₁,B₆ H₁₀, B₆ H1₂, and AlCl₃.

EXAMPLE 1

Using an apparatus as shown in FIG. 2, a drum type ofelectrophotographic image forming member was prepared in the followingmanner.

In FIG. 2, numerals denote the following: 1: a deposition space (A), 2:a decomposition space (B), 3: a decomposition space (C), 4: an electricfurnace, 5: solid Si grains, 6: an inlet pipe for feeding a startingmaterial for a precursor, 7: a conduit for the precursor; 8: an electricfurnace, 9: an inlet pipe for a starting material for activated species,10: an conduit for the activated species, 11: a motor, 12: a heater, 13:a precursor blowoff pipe, 14: an activated species blowoff pipe, 15: anAl cylinder, and 16: an exhaust valve.

An Al cylinder 15 was suspended in the deposition space (A) 1. Theheater 12 was set inside the cylinder so that it may be rotated by themotor 11.

The apparatus comprises the conduit 7 for introducing the precursor fromthe decomposition space (B) 2, the blowoff pipe 13 for the precursor,the conduit 10 for introducing the activated species from thedecomposition space (C) 3 and the blowoff pipe 14 for the activatedspecies.

The solid Si grains 5 filled in the decomposition space (B) 2 weremelted by heating with the electric furnace 4. While keeping thetemperature of the Si melt at 1100° C., SiF₄ was blown thereinto from abomb through the inlet pipe 6 to form a precursor SiF₂. The SiF₂-containing gas was then introduced into the deposition space (A) 1through the conduit 7 and the blowoff pipe 13.

On the other hand, SiH₄ and H₂ were fed into the decomposition space(C)3 through the inlet pipe 9, and heated at 600° C. with the electricfurnace 8 to form activated species such as SiH₂, SiH, SiH₃, and H. Theactivated species-containing gas was introduced into the depositionspace (A)1 through the conduit 10 and the blowoff pipe 14. Herein thelength of the conduit 10 had been designed as short as possible tominimize the deactivation of the activated species during the passagetherethrough. The Al cylinder in the deposition space (A) is heated at300° C. by the heater 12 and rotated. The waste gas was dischargedthrough the exhaust valve 16. Thus a 20-μ thick photoconductive layer103 was formed. Similarly, an intermediate layer 102 and surface layer104 were formed.

EXAMPLE 2

An amorphous silicon deposition film was formed by the conventionalplasma CVD process using an apparatus as shown in FIG. 2, the depositionspace (A) of which was provided with a 13.56-MHz high-frequency electricdischarge unit. At that time, SiF₄, SiH₄ and H₂ were employed.

EXAMPLE 3

An electrophotographic image forming member in the drum form wasprepared in the same manner as in Example 1 except that, for theformation of the photoconductive layer, H₂ was fed, instead of the SiH₄/H₂ mixture, into the decomposition space (C)3 and a plasma reaction wascaused to take place by a 13.56-MHz high-frequency electric dischargewithout heating with the electric furnace so that the hydrogen plasmastate was produced. The activated species of H was introduced into thedeposition space (A) through the blowoff pipe 14.

The preparation conditions and performance of the electrophotographicimage forming member in the drum form obtained in Examples 1, 2 and 3are shown in Table 1.

In Examples 1 and 3, the intermediate layer 102 (2000Å thick) was formedin such a manner that SiF₄ and SiH₄ /H₂ /NO/B₂ H₆ (NO 2% and B2H₆ H₆0.2% by vol. %) were introduced into the decomposition spaces (B) and(C), respectively, and the precursor and activated species were producedwith the respective excitation energies and introduced into thedeposition space (A).

Also, in Example 2, the intermediate layer (2000Å thick) was formed bythe plasma CVD process employing a gas mixture of SiH₄ /H₂ /NO/B₂ H₆ ofthe same composition as that in Examples 1 and 3.

In Examples 1 and 3, the surface layer 104 (1000Å thick) was formed insuch a manner that SiF₄ was introduced into the decomposition space (B)while SiH₄ /CH₄ /H₂ was introduced in volume ratio of 10:100:50 into thedecomposition space (C), and the precursor and activated species wereproduced with the respective excitation thermal energies and introducedinto the deposition space (A).

Also in Example 2, the plasma CVD process was carried out employing SiHof the same composition as above to form the surface layer 104 (1000Åthick).

Electrophotographic image forming drums prepared in Examples 1, 2, and 3were each set in a copying machine of Carlson process type comprisingthe positive charging, image exposure, development with a negativetoner, image transfer, and heat fixing, and A3-size copies of blackimage, white image and gray image were made. Irregularities on theresulting images were examined and expressed by the average number ofimage defects. The uniformity of charged potential on the cylindersurface in the circumferential and axial directions was also evaluated.Results thereof are shown in Table 1.

EXAMPLE 4

Using an apparatus as shown in FIG. 3, electrophotographic image formingmembers in drum form were prepared under similar conditions as inExample 1.

In FIG. 3, numerals 7, 10, 13, 14, 15, and 16 have the same meaning asin FIG. 2, and 17 denotes a movable stand provided with rotating means,18 a cooling space, 19 a heating space, and 20 a deposition space.

As shown in FIG. 3, the apparatus employed in this example comprised aheating chamber 19, deposition chamber 20, and cooling chamber 18. A1cylinders 15 were placed on the movable stand 17 provided with rotatingmeans. In the apparatus, a number of A1 cylinders could be treated atonce in one deposition space to produce electrophotographic imageforming members in the drum form continuously.

It has been confirmed that electrophotographic image forming members inthe drum form having uniform and reproducible deposition films can bemass-produced at a low cost by controlling the temperatures of thedeposition space and of the A1 cylinders and the flow amounts of theprecursor-containing gas blown out from the pipe 13 through the conduit7 from the decomposition space (B) and of the activatedspecies-containing gas blown out from the pipe 14 through the conduit 10from the decomposition space (C).

According to the plasma CVD process, such treatment of a number ofcylindrical substrates in one deposition space would involve problems inthe uniformity of the electric discharge and in synergistic effects ofcomplicated production condition parameters, so that it has beenimpossible to produce electrophotographic image forming member in thedrum form having uniform deposition films with high reproducibility.

EXAMPLE 5

Using an apparatus as shown in FIG. 4, an electrophotographic imageforming drum was prepared.

In FIG. 4, numerals denote the following: 20: a deposition space, 21: ahigh-frequency power source (13.56 MHz), 22: a plasma space, 23: a50-mesh stainless steel gauze, 24: a substrate, 25: a support table, 26:an earth for keeping the same potential, 27: a blowoff pipe for aprecursor-containing gas or activated species-containing gas from adecomposition space (B), 28: a blowoff pipe for an SiH₄ /H₂ mixture, 29:a deposition space (A), 30: an exhaust valve.

Thus, using the apparatus, which had the decomposition space (C) and thedeposition space (A) in the same chamber and separately thedecomposition space (B), SiF₂ was produced in the decomposition space(B) in the same manner as in Example 1 and the SiF₂ -containing gas wasintroduced into the deposition space (A) while as SiH₄ /H₂ mixture wasintroduced into the decomposition space (C), where a plasma wasgenerated and reacted with SiF₂. The resulting gas was passed throughthe gauze 23 and amorphous silicon was deposited therefrom on thesubstrate which was kept at a temperature of 280° C. in the depositionspace (A). The deposited photoconductive layer exhibited goodcharacteristics, e.g. a dark conductivity, V_(D), of 2×10¹¹Ω-1 cm⁻¹ anda light conductivity, V_(P), of 3×10⁶Ω-1 cm⁻¹.

EXAMPLE 6

An electrophotographic image forming member in the drum form wasprepared by using an apparatus as shown in FIG. 2.

The photoconductive layer 103 thereof was formed as follows: An A1cylinder 15, suspended in the deposition space (A)1, was rotated andheated at 300° C. by the heater 12 which was set inside the A1 cylinderand rotated by the motor 11.

The solid Si grains 5 filled in the decomposition space (B)2 were meltedby heating with the electric furnace 4. While keeping the temperature ofthe Si melt at 1100° C., SiF₄ was blown thereinto from a bomb throughthe inlet pipe 6 to form an activated species of SiF₂. The SiF₂-containing gas was then introduced into the deposition space (A)1through the conduit 7 and the blowoff pipe 13.

On the other hand, an Si₂ H₆ /H₂ (vol. ratio 5:5) mixture was fed intothe decomposition space (C) 3 through the inlet pipe 9, and heated at450° C. with the electric furnace 8 to form activated species such asSiH₂, SiH, SiH₃, and H. The activated species-containing gas was thenintroduced into the deposition space (A)1 through the conduit 10 and theblowoff pipe 14. Herein the conduit 10 has been designed as short aspossible to minimize the deactivation of the activated species duringthe passage therethrough. Thus, the photoconductive layer 103 (21 μthick) was formed. The waste gas was discharged through the exhaustvalve 16.

Similarly, the intermediate layer 102 and surface layer 104 were formed.

EXAMPLE 7

A photoconductive layer 103 was formed from SiF4, Si₂ H₆ and H₂ by theconventional plasma CVD process using an apparatus as shown in FIG. 2,the deposition space (A)1 of which was provided with a 13.56-MHzhigh-frequency electric discharge unit.

EXAMPLE 8

A deposition film was formed in the same manner as in Example 6, exceptthat an SiH₄ /Si₃ H₈ /H₂ (vol. ratio 2:1:1) mixture was fed as startinggas into the decomposition space (C)3, and a plasma reaction was causedto take place by applying a 13.56-MHz high-frequency electric field tothe mixture instead of heating with the electric furnace so that ahydrogen plasma state was produced. The activated species of H andvarious silanes were introduced to the blowoff pipe 14. In such amanner, an electrophotographic image forming member in the drum form wasprepared.

EXAMPLE 9

An electrophotographic image forming member in the drum form wasprepared in the same manner as in Example 6, except that, for theformation of the photoconductive layer, Si₂ F₆ was fed as the startinggas into the decomposition space (B) and an Si₂ H₆ /H₂ (vol. ratio 5:5)mixture was fed into the decomposition space (C) and heated at 450° C.with the electric furnace to produce activated species of hydrogen andof silane.

The preparation conditions and performance of the electrophotographicimage forming member in the drum form obtained in Examples 6, 7, 8 and 9are shown in Table 2.

In Examples 6, 8 and 9, the intermediate layer 102 (2000Å thick) wasformed in such a manner that SiF₄ and Si₂ H₆ /H₂ /NO/B₂ H₆ (NO 2 % andB₂ H₆ 0.2% by vol.%) were introduced into the decomposition spaces (B)and (C), respectively, and activated species were produced with therespective excitation energies and introduced into the deposition space(A).

Also, in Example 7, the intermediate layer (2000Å thick) was formed bythe plasma CVD process employing a gas mixture of Si₂ H₆ /H₂ /NO/B₂ H₆of the same composition as that in Examples 6, 8 and 9.

In Examples 6, 8 and 9, the surface layer 104 (1000Å thick) was formedin such a manner that SiF₄ was introduced into the decomposition space(B) while Si₂ H₆ /CH₄ /H₂ was introduced in volume ratio of 10:100:50into the decomposition space (C), and activated species were producedwith the respective excitation thermal energies and introduced into thedeposition space (A).

Also in Example 7, the plasma CVD process was carried out employing Si₂H₆ /CH₄ /H₂ of the same composition as above to form the surface layer104 (1000Å thick).

EXAMPLE 10

Using an apparatus as shown in FIG. 3, electrophotographic image formingmembers in the drum form were prepared continuously under similarconditions as in Example 6.

It has been confirmed that electrophotographic image forming members inthe drum form having uniform and reproducible deposition films can bemass-produced at low costs by controlling the temperatures of thedeposition space and of the A1 cylinders and the flow amounts of theactivated species-containing gas from the decomposition space (B) and ofthe activated species-containing gas from the decomposition space (C)into the deposition space (A).

According to the plasma CVD process, such treatment of a number ofcylindrical substrates in one deposition space would involve problems inthe uniformity of the electric discharge and in synergistic effects ofcomplicated production condition parameters, so that it has beenimpossible to produce electrophotographic image forming member in thedrum for having uniform deposition films with high reproducibility.

EXAMPLE 11

An electrophotographic image forming member in the drum form wasprepared in the same manner as in Example 6 except that, for theformation of the photoconductive layer, a mixture of SiH₄ and H₂ (volratio 1:1) was used as the starting gas introduced into thedecomposition space (C)3 and heated at 600° C. by the electric furnaceto produce the activated species of silane and hydrogen. The surfacelayer 104 and intermediate layer 102 were formed similarly.

Electrophotographic image forming members in the drum form prepared inExamples 6, 7, 8, 9, and 11 were evaluated in the same manner as in thecase of Examples 1, 2, and 3. Results thereof are shown in Table 2together with operational conditions in the formation of thephotoconductive layers.

EXAMPLE 12

An electrophotographic image forming member in the drum form wasprepared by using an apparatus as shown in FIG. 2.

The photoconductive layer thereof was formed as follows: An A1 cylinder15, suspended in the deposition space (A)1, was rotated and heated at280° C. by the heater 12 which was set inside the A1 cylinder androtated by the motor 11.

The solid Si grains 5 filled in the decomposition space (B)2 were meltedby heating with the electric furnace 4. While keeping the temperature ofthe Si melt at 1100° C., SiF₄ was blown thereinto from a bomb throughthe inlet pipe 6 to form an activated species of SiF₂ The SiF₂-containing gas was then introduced into the deposition space (A)1through the conduit 7 and the blowoff pipe 13.

On other hand, (SiH₂)₅ was fed into the decomposition space (C)3 throughthe inlet pipe 9, and heated at 300° C. with the electric furnace 8 toproduce activated species such as SiH₂, SiH, SiH₃, and H. The activatedspecies-containing gas was then introduced into the deposition space(A)1 through the conduit 10 and the blowoff pipe 14. Herein the conduithad been designed as short as possible to minimize the deactivation ofthe activated species during the passage therethrough. Thus, thephotoconductive layer 103 (20 μ thick) was formed. The waste gas wasdischarged through the exhaust valve 16. Similarly, the intermediatelayer 102 and surface layer 104 were formed.

EXAMPLE 13

A photoconductive layer 103 was formed from SiF₄, Si₂ H₆ and H₂ by theconventional plasma CVD process using an apparatus as shown in FIG. 2,the deposition space (A)1 of which was provided with a 13.56-MHzhigh-frequency electric discharge unit.

EXAMPLE 14

An electrophotographic image forming member in the drum form wasprepared in the same manner as in Example 12, except that, for theformation of the photoconductive layer 103, an SiH₄ /(SiH₂)₅ (vol ratio1:1) mixture was fed as starting gas into the decomposition space (C)3,and a plasma reaction was caused to take place by applying a 13.56-MHzhigh-frequency electric field to the mixture instead of heating with theelectric furnace so that a plasma state was produced. The activatedspecies of various silanes and H were then introduced into the blowoffpipe 14. In this manner, a desired image forming member was obtained.

EXAMPLE 15

An electrophotographic image forming member in the drum form wasprepared in the same manner as in Example 12, except that, for theformation of the photoconductive layer, an (SiH₂)₄ /(SiH₂)₅ /H₂ (vol.ratio 1:1:1) mixture was fed as starting gas into the decompositionspace (C) and heated at 320° C. with the electric furnace to produceactivated

EXAMPLE 16

An electrophotographic image forming member in the drum form wasprepared in the same manner as in Example 12, except that, for theformation of the photoconductive layer, Si₂ F₆ as starting gas was fedinto the decomposition space (B) and (SiH₂)₅ was fed as starting gasinto the decomposition space (C) and heated at 300° C. with the electricfurnace to produce activated species of silanes and of hydrogen.

EXAMPLE 17

An electrophotographic image forming member in the drum form wasprepared in the same manner as in Example 12, except that, for theformation of the photoconductive layer, an Si₂ H₆ /(SiH₂)₅ (vol. ratio1:1) mixture was fed as starting gas into the decomposition space (C)and heated at 310° C. with the electric furnace to produce activatedspecies of silanes and of hydrogen.

The preparation conditions and performance of the electrophotographicimage forming member in the drum form obtained in Examples 12, 13, 14,15, 16 and 17 are shown in Table 3.

In Examples 12, 14, 15, 16 and 17, the intermediate layer 102 (2000Åthick) was formed in such a manner that SiF₄ and (SiH₂)₅ /H₂ /NO/B₂ H₆(NO 2% and B₂ H₆ 0.2% by vol. %) were introduced into the decompositionspaces (B) and (C), respectively, and activated species were producedwith the respective excitation energies and introduced into thedeposition space (A).

Also, in Example 13, the intermediate layer (2000Å thick) was formed bythe plasma CVD process employing a gas mixture of (SiH₂)₅ /H₂ /NO/B₂ H₆of the same composition as that in Examples 12 and 14.

In Examples 12, 14, 15, 16 and 17, the surface layer 104 (1000Å thick)was formed in such a manner that SiF₄ was introduced into thedecomposition space (B) while (SiH₂)₅ /CH₄ /H₂ was introduced in volumeratio of 10:100:50 into the decomposition space (C), and activatedspecies were produced with the respective excitation thermal energiesand introduced into the deposition space (A).

Also in Example 13, the plasma CVD process was carried out employing(SiH₂)₅ /CH₄ /H₂ of the same composition as above to form the surfacelayer 104 (1000 Å thick).

Electrophotographic image forming drums prepared in Examples 12, 13, 14,15, 16 and 17 were evaluated in the same manner as in the case ofExamples 1, 2, and 3. Results thereof are shown the formation of thephotoconductive layers.

EXAMPLE 18

Using an apparatus as shown in FIG. 3, electrophotographic image formingmembers in the drum form were prepared continuously under similarconditions as in Example 12.

It has been confirmed that electrophotographic image forming members inthe drum form having uniform and reproducible deposition films can bemass-produced at a low cost by controlling the temperatures of thedeposition space and of the A1 cylinders and the flow amounts of theactivated species-containing gas from the decomposition space (B), andof the activated species-containing gas from the decomposition space (C)into the deposition space (A).

According to the plasma CVD process, such treatment of a number ofcylindrical substrates in one deposition space would involve problems inthe uniformity of the electric discharge and in synergistic effects ofcomplicated production condition parameters, so that it has beenimpossible to produce electrophotographic image forming member in thedrum form having uniform deposition films with high reproducibility.

                                      TABLE 1                                     __________________________________________________________________________    Item          Example 1                                                                             Example 2                                                                              Example 3                                      __________________________________________________________________________    Decomp. space (B)                                                             Feed gas      SiF.sub.4        SiF.sub.4                                      Decomp. temp. 1100° C.  1100° C.                                Main precursor                                                                              SiF.sub.2 *      SiF.sub.2 *                                    Decomp. space (C)                                                             Feed gas (vol. ratio)                                                                       SiH.sub.4 /H.sub.2                                                                             H.sub.2                                                      (1:1)                                                           Decomp. energy                                                                              Heat, 600° C.                                                                           Plasma RF 150 W                                Activated species                                                                           SiH.sub.2 *, SiH*,                                                                             H*                                                           SiH.sub.3 *, H*, Si*                                            Deposition space (A)                                                          Inflow from (B)                                                                             200 SCCM         200 SCCM                                       Inflow from (C)                                                                             100 SCCM         80 SCCM                                        Inflow from bomb      SiF.sub.4 200 SCCM                                                            SiH.sub.4 100 SCCM                                                            H.sub.2 100 SCCM                                        Pressure in (A)                                                                             1.0 Torr                                                                              1.0 Torr 0.8 Torr                                       Substrate temp.                                                                             280° C.                                                                        260° C.                                                                         280° C.                                 Temp. in (A)  250° C.   250° C.                                 Rate of deposition                                                                          15 Å/sec                                                                          5 Å/sec                                                                            12 Å/sec                                   Plasma RF             130 W                                                   Thickness of photoconduc-                                                                   20μ  17μ   22μ                                         tive layer                                                                    Average number of image                                                                     2       15       3                                              defects per each of 10 drums                                                  Deviation of charged                                                                        ±10 V                                                                              ±30 V ±8 V                                        potentials distributed in                                                     circumferential direction                                                     Deviation of charged                                                                        ±15 V                                                                              ±35 V ±15 V                                       potentials distributed in                                                     axial direction                                                               Nature of process                                                                           Process of                                                                            Conventional                                                                           Process of                                                   this    plasma CVD                                                                             this                                                         invention                                                                             process  invention                                      __________________________________________________________________________

                                      TABLE 2                                     __________________________________________________________________________    Item       Example 6                                                                            Example 7                                                                              Example 8                                                                              Example 9                                                                            Example 11                         __________________________________________________________________________    Decomp. space (B)                                                             Feed gas   SiF.sub.4       SiF.sub.4                                                                              Si.sub.2 F.sub.6                                                                     SiF.sub.4                          Decomp. temp.                                                                            1100° C. 1100° C.                                                                        800° C.                                                                       1100° C.                    Main precursor                                                                           SiF.sub.2 *     SiF.sub.2 *                                                                            SiF.sub.2 *                                                                          SiF.sub.2 *                        Decomp. space (C)                                                             Feed gas   Si.sub.2 H.sub.6 /H.sub.2                                                                     SiH.sub.4 /Si.sub.3 H.sub.8 /H.sub.2                                                   Si.sub.2 H.sub.6 /H.sub.2                                                            SiH.sub.4 /H.sub.2                 (vol. ratio)                                                                             (5:5)           (10:5:5) (5:5)  (1:1)                              Decomp. energy                                                                           Heat 450° C.                                                                           Plasma RF 100 W                                                                        Heat 450° C.                                                                  Heat 600° C.                Activated species                                                                        SiH.sub.2 *, SiH*                                                                             Similar to                                                                             Similar to                                                                           Similar to                                    Si*, SiH.sub.3 *                                                                              Example 6                                                                              Example 6                                                                            Example 6                                     Si.sub.2 H.sub.5 *, H*                                             Decomp. space (A)                                                             Inflow from (B)                                                                          150 SCCM        140 SCCM 120 SCCM                                                                             200 SCCM                           Inflow from (C)                                                                          80 SCCM         75 SCCM  80 SCCM                                                                              100 SCCM                           Inflow from bomb  SiF.sub.4 200 SCCM                                                            Si.sub.2 H.sub.6 100 SCCM                                                     H.sub.2 100 SCCM                                            Pressure in (A)                                                                          1.1 Torr                                                                             1.2 Torr 1.2 Torr 1.0 Torr                                                                             1.0 Torr                           Substrate temp.                                                                          270° C.                                                                       260° C.                                                                         270° C.                                                                         270° C.                                                                       280° C.                     Temp. in (A)                                                                             250° C.  250° C.                                                                         250° C.                                                                       250° C.                     Rate of deposition                                                                       20 Å/sec                                                                         8 Å/sec                                                                            21 Å/sec                                                                           21 Å/sec                                                                         15 Å/sec                       Plasma RF         130 W                                                       Thickness of photo-                                                                      21μ 18μ   22μ   21μ 20μ                             conductive layer                                                              Average number of                                                                        2      17       3        2      2                                  image defects per                                                             each of 10 drums                                                              Deviation of charged                                                                     ±10 V                                                                             ±30 V ±8 V  ±11 V                                                                             ±10 V                           potentials distri-                                                            buted in circumfer-                                                           ential direction                                                              Deviation of charged                                                                     ±13 V                                                                             ±35 V ±15 V ±12 V                                                                             ±15 V                           potentials distri-                                                            buted in axial                                                                direction                                                                     Nature of process                                                                        Process of                                                                           Conventional                                                                           Process of                                                                             Process of                                                                           Activated                                     this   plasma CVD                                                                             this     this   species of                                    invention                                                                            process  invention                                                                              invention                                                                            monosilane                                                                    SiH.sub. 4 is                                                                 used                               __________________________________________________________________________

                                      TABLE 3                                     __________________________________________________________________________    Item      Example 12                                                                           Example 13                                                                          Example 14                                                                           Example 15                                                                          Example 16                                                                          Example 17                          __________________________________________________________________________    Decomp. space (B)                                                             Feed gas  SiF.sub.4    SiF.sub.4                                                                            SiF.sub.4                                                                           Si.sub.2 F.sub.6                                                                    SiF.sub.4                           Decomp. temp.                                                                           1100° C.                                                                            1100° C.                                                                      1100° C.                                                                     1100° C.                                                                     1100° C.                     Main precursor                                                                          SiF.sub.2 *  SiF.sub.2 *                                                                          SiF.sub.2 *                                                                         SiF.sub.2 *                                                                         SiF.sub.2 *                         Decomp. space (C)                                                             Feed gas  (SiH.sub.2).sub.5                                                                          SiH.sub.4 /(SiH.sub.2).sub.5                                                         (SiH.sub.2).sub.4 /                                                                 (SiH.sub.2).sub.5                                                                   Si.sub.2 H.sub.6 /(SiH.sub.2).su                                              b.5                                 (vol. ratio)           (1:1)  (SiH.sub.2).sub.5 /H.sub.2                                                                (1:1)                                                             (1:1:1)                                         Decomp. energy                                                                          Heat         Plasma RF                                                                            Heat  Heat  Heat                                          300° C.                                                                             150 W  320° C.                                                                      300° C.                                                                      310° C.                      Activated species                                                                       SiH.sub.2 *, H*                                                                            Similar to                                                                           Similar to                                                                          Similar to                                                                          Similar to                                    SiH.sub.3 *, SiH*                                                                          Example 12                                                                           Example 12                                                                          Example 12                                                                          Example 12                                    Si*                                                                 Decomp. space (A)                                                             Inflow from (B)                                                                         150 SCCM     135 SCCM                                                                             180 SCCM                                                                            130 SCCM                                                                            170 SCCM                            Inflow from (C)                                                                         70 SCCM      60 SCCM                                                                              100 SCCM                                                                            70 SCCM                                                                             100 SCCM                            Inflow bomb      SiF.sub.4                                                                     200 SCCM                                                                      Si.sub.2 H.sub.6                                                              100 SCCM                                                                      H.sub.2                                                                       100 SCCM                                                     Pressure in (A)                                                                         1.1 Torr                                                                             1.0 Torr                                                                            1.0 Torr                                                                             1.2 Torr                                                                            1.1 Torr                                                                            1.2 Torr                            Substrate temp.                                                                         260° C.                                                                       260° C.                                                                      270° C.                                                                       270° C.                                                                      260° C.                                                                      260° C.                      Temp. in (A)                                                                            250° C.                                                                             250° C.                                                                       250° C.                                                                      200° C.                                                                      250° C.                      Rate of   31 Å/sec                                                                         5 Å/sec                                                                         26 Å/sec                                                                         33 Å/sec                                                                        35 Å/sec                                                                        35 Å/sec                        deposition                                                                    Plasma RF        130 W                                                        Thickness of                                                                            20μ 17μ                                                                              21μ 20μ                                                                              20μ                                                                              20μ                              photoconductive                                                               layer                                                                         Average number                                                                          1      15    3      2     1     2                                   of image defects                                                              per each of                                                                   10 drums                                                                      Deviation of                                                                            ±10 V                                                                             ±30 V                                                                            ±8 V                                                                              ±5 V                                                                             ±8 V                                                                             ±4 V                             charged potential                                                             distributed in                                                                circumferential                                                               direction                                                                     Deviation of                                                                            ± 12 V                                                                            ±35 V                                                                            ±14 V                                                                             ±12 V                                                                            ±13 V                                                                            ±10 V                            charged potential                                                             distributed in                                                                axial direction                                                               Nature of Process                                                                              Conven-                                                                             Process                                                                              Process                                                                             Process                                                                             Process                             process   of this                                                                              tional                                                                              of this                                                                              of this                                                                             of this                                                                             of this                                       invention                                                                            plasma                                                                              invention                                                                            invention                                                                           invention                                                                           invention                                            CVD                                                                           process                                                      __________________________________________________________________________

What is claimed is:
 1. A process for forming a desposition film suitablefor use in semiconductor devices or electrophotographic photosensitivedevices on a substrate in a deposition space (A), whichComprises:forming a gaseous activated species (a) by decomposing astarting material selected from the group consisting of the compounds ofthe formulas: Si_(n) X_(2n+2) (SiX_(2-n) (n≧3) Si_(n) HX_(2n+1) Si_(n)H₂ X_(2n) wherein n is an integer of at least 1 and X is selected fromthe group consisting of F, Cl, Br or I in a decomposition space forminga gaseous activated species (b) by decomposing another starting materialwherein said another material is selected from the group consisting of ahigher straight chain silane compound and a cyclic silane compound in adecomposition space (c); and separately introducing said gaseousactivated species (a) and said gaseous activated species (b) into thedeposition space, wherein the activated species is capable of undergoingchemical interaction with activated species (a) to form the film on thesubstrate, said process being conducted without exposing a film-formingsurface of the substrate to a plasma atmosphere.
 2. The process of claim1, wherein the activated species formed in the decomposition space havelifetimes of at least 1 second.
 3. The process of claim 1, wherein theactivated species formed in the decomposition space have lifetimes of atleast 150 seconds.
 4. The process of claim 1, wherein the activatedspecies formed in the decomposition space (C) has a lifetime of at most10 seconds.
 5. The process of claim 1, wherein the ratio of the volumeof the activated species from the decomposition space (B) to the volumeof the activated species from the decomposition space (C) is 10:1 to1:10 at the deposition space (A).
 6. A process for forming a depositionfilm on a substrate in deposition space (A) which comprises introducingseparately activated species which are prepared by decomposing a siliconhalide represented by the formula Si_(n) X_(2n+2) and a mixture ofactivated species of hydrogen with activated species (b) represented bythe formula Si_(m) H_(2m-x), the mixture being prepared by decomposing ahigher, straight chain silane compound, into the deposition space (A)wherein the film is formed on the substrate and wherein n, m, and x areeach integers of at least
 1. 7. A process for forming a deposition filmin a substrate in a deposition space (A) on which comprises introducingseparately activated species (a) which are prepared by decomposing asilicon halide represented by the formula Si_(n) X_(2n+2), wherein n isan integer of at least 1, and a mixture of activated species of hydrogenwith activated species (b), the mixture being prepared by decomposing acyclic silane compound, into the deposition space (A) wherein the filmis formed on the substrate.
 8. The process of claim 1, wherein theactivated species (a) are formed by utilizing any of electric dischargeenergy, thermal energy, and light energy.
 9. The process of claim 1,wherein the activated species (a) formed include a p-type or n-typeimpurity.
 10. The process of claim 6, wherein the activated species (a)are formed by utilizing any of electric discharge energy, thermalenergy, and light energy.
 11. The process of claim 6, wherein theactivated species (a) formed include a p-type or n-type impurity. 12.The process of claim 7, wherein the activated species (a) are formed byutilizing any of electric discharge energy, thermal energy, and lightenergy.
 13. The process of claim 7, wherein the activated species (a)formed include a p-type or n-type impurity.
 14. A process for forming adeposition film suitable for use in semiconductor devices ofelectrophotographic photosensitive devices on a substrate in adeposition space, which comprises:forming a gaseous activated species bydecomposing a starting material in a decomposition space wherein saidgaseous activated species has a lifetime of at least 1 second; forming agaseous activated species by decomposing another starting material in adecomposition space wherein said gaseous activated species has alifetime of at most 10 seconds; and separately introducing said gaseousactivated species and said gaseous activated species into the depositionspace, wherein the activated species is capable of undergoing chemicalinterraction with activated species to form the film on the substrate,said process being conducted without exposing a film-forming surface ofthe substrate to a plasma atmosphere.
 15. The process of claim 14,wherein the activated species formed in the decomposition space havelifetimes of at least 150 seconds.
 16. The process of claim 14, whereinthe material to be fed into the decomposition space to form activatedspecies is selected from the group consisting of the compounds of theformulas:Si_(n) X_(2n+2) (SiX₂)_(n) (n≧3) Si_(n) HX_(2n+) Si_(n) H₂X_(2n) wherein n is an integer of at least 1 and X is selected from thegroup consisting of F,Cl, Br, or I.
 17. The process of claim 14, whereinthe material to be fed into the decomposition space to form activatedspecies is a higher straight chain silane compound.
 18. The process ofclaim 14, wherein the material to be fed into the decomposition space toform activated species is a cyclic silane compound.
 19. The process ofclaim 14, wherein the amount ratio of the activated species from thedecomposition space to the activated species from the decompositionspace is 10:1 to 1:10 at the deposition space.
 20. The process of claim14, wherein the activated species are formed by utilizing any ofelectric discharge energy, thermal energy, and light energy.
 21. Theprocess of claim 14, wherein the activated species formed include ap-type or n-type impurity.
 22. The process of claim 14 includingemploying said activated species containing silicon atoms.